As an important acoustic component in portable electronic devices, a loudspeaker is an energy conversion device for converting sound wave electrical signals to sound signals and transmitting it out. A loudspeaker usually comprises a vibrating system and a magnetic circuit system. The vibrating system comprises a vibrating diaphragm and a voice coil combining together, and the voice coil is the driving component of the loudspeaker. When an alternating voice current passes through the voice coil, the voice coil generates a magnetic field changing with the voice current. The changing magnetic field and the magnetic field of the magnetic circuit system of the loudspeaker attract or repulse to enable the voice coil to generate mechanical vibration that cuts the magnetic field lines, thereby driving the vibrating diaphragm to vibrate and make sound. The conventional voice coils are usually wound by voice coil wires having a circular cross-section, the structure of which is shown in FIG. 1. As shown in FIG. 1, the voice coil is wound by a voice coil wire 10a having a circular cross-section. Gaps will inevitably occur in the winding process of the voice coil wire of such a structure. Moreover, the conductors occupy a small proportion of the sectional area of the voice coil while magnetic gaps occupy more space. Therefore, the voice coil has a low volume utilization ratio, and the presence of air gaps adversely affects heat dissipation of the voice coil.
Presently, products are required to be lighter and thinner and have more power and better heat dissipation. In order to achieve these objects, it is required to more effectively use the air gaps existing between the circular voice coil wires. Usually, the compression method is used to reduce the air gaps between the voice coil wires. However, the compression method cannot completely eliminate the air gaps. Moreover, it has the problems that compression will rupture the insulation layer of the voice coil wire and result in a short circuit, and the glue adhesive force between the layers will be destroyed or reduced. In addition, the compression is irregular, and the wires cannot be controlled to be uniformly compressed.
There is also a voice coil wire having a square cross-section. This type of voice coil wire effectively improves the volume utilization ratio of the voice coil. However, inclination will occur during winding and changing the square wire, and inclination and distortion will occur when arranging two and more layers of the voice coil wires, which also results in many air gaps. In addition, the winding process is complicated, and the shape of voice coil obtained is irregular.